1. Field of the Invention
The present invention relates to operations in a wellbore associated with the production of hydrocarbons. More specifically, the invention relates to a tool for use in wellbores.
2. Description of the Related Art
Downhole tools are used in the hydrocarbon industry for well intervention, reservoir characterization, and pipe recovery. Downhole tools can provide well information and perform well services such as depth correlation, wellbore flow characterization, cement integrity evaluations, wellbore diagnostic operations, and remedial operations. Logs constantly retrieve measurements downhole via communication lines such as electrical wireline. Logs can measure resistivity, conductivity, porosity, wave transmit time and so forth. These critical parameters are of paramount importance for geologists, drilling, reservoir, and production engineers from which vital decisions are made during various phases of exploration and development. Furthermore, logs are used frequently in workover operations where wells need remedial work in order to flow efficiently.
Often in the recovery of hydrocarbons from subterranean formations, wellbores are drilled with highly deviated or horizontal portions that can extend through one or a number of separate hydrocarbon-bearing production zones. Tractors are used to force tool string, such as coiled tubing, wireline and slickline, into the hole in highly deviated and horizontal wells where gravity does not play any crucial role.
Coiled tubing can retain some amount of residual curvature as the coiled tubing is rolled off of the coiled tubing reel and fed down the wellbore. The residual curvature as well as the bends and deviations of the wellbore can cause the coiled tubing to engage the sidewall of the wellbore and generate frictional resistance. If the frictional resistance reaches a certain level, the coiled tubing can no longer be pushed into the wellbore. This phenomenon is known as coiled tubing lockup or helical lock up. Coiled tubing lock up is major issue related to access of the wellbore. At times, up to 75% of some wellbores have no direct coiled tubing access and given the magnitude of frictional resistance that must be overcome, conventional well tractors can't always get the coiled tubing and associated tools to the desired location within the wellbore or to the well total depth.
Conventional tractors can use wheels to push against the side of the wellbore, which increases the force required to push the wireline tools. The use of tractors with wheels increases the gross size of the tool, which is a significant parameter in determining the appropriate type of tractors that could be used for diverse sized holes.